The present invention relates to the storage of energy producing fluids for subsequent use, and more particularly, relates to the utilization of a previously used or abandoned railroad, highway or aqueduct tunnel structure as an integral part of a compressed air, compressed or liquefied natural gas, or liquefied propane or butane storage system. It would be used, for example, as a xe2x80x9cpeakingxe2x80x9d service facility, or as a base storage facility for liquefied propane or butane. The invention also provides for the on-site generation of electricity utilizing the energy producing fluids.
The need for natural gas for service requirements during peak demand times can occur at several periods during the year. In the summer, for example, natural gas may be used to generate electricity to meet peaking requirements at times of high electric demand. In the winter, natural gas may be used to meet heating and electric requirements when the temperatures are extremely low. Typically the value of natural gas in the winter season is inversely proportional to the temperature below fifteen degrees Fahrenheit. In the summer, the value of natural gas typically becomes most significant when temperatures exceed ninety degrees Fahrenheit.
The best economics for using natural gas storage in peaking cycles traditionally depends on buying the material xe2x80x9coff seasonxe2x80x9d and using it in xe2x80x9cpeak seasonxe2x80x9d. The traditional means of storing natural gas is in underground leached salt caverns, in depleted gas fields, and in insulated structures, which are designed to hold liquefied natural gas and are most typically above ground. In a very limited number of situations storage at high pressure has also been done utilizing a multiplicity of relatively smaller volume steel or reinforced plastic cylinders that are buried in the ground. Typically, the use of reinforced plastic cylinders has been in conjunction with compressed natural gas fueling stations. In those cases the volumes involved are significantly smaller than traditional storage volumes. When there is a multiplicity of tanks, the tanks are normally manifolded together to effectively act as a single storage unit. The facilities for all of the above provide for putting the fluid, natural gas, into the storage medium, and for removal of the fluid when required. The rate of removal is traditionally many times the rate of injection. This invention would allow removal of natural gas at very high or low rates dependent upon market conditions.
The traditional underground storage fields for natural gas are often remote from the principal markets to which the gas is delivered, particularly markets in the Northeast. The use of abandoned or inactive railroad, highway or aqueduct tunnels, or similar structures, would be utilized by this invention, and may, in many cases, provide for much closer proximity to the principal markets, reducing time and delivery costs significantly. By its nature, an inactive or abandoned railroad tunnel, particularly when adjacent to a still active railroad line would allow: (1) for economic delivery of not only material required for construction of a storage facility, but also (2) for subsequent delivery into storage of LNG fuel directly by railroad car as contemplated by this invention. The larger volume of a railroad car, as compared to a truck, when utilized for LNG transport may provide a lower economic per unit delivery cost to the facility, thus offering a significant operating cost benefit. The same cost advantage will apply for delivery of liquefied propane or butane by railcars.
When compressed natural gas or compressed air is stored in steel cylinders at high pressure, the cylinders have commonly been buried in trenches in a single layer, and, in a very limited number of cases, in vertical holes drilled for the purpose. The land required to provide a significant volume of stored compressed natural gas (CNG) or air in this manner can thus be extensive.
Large volumes of liquefied propane or butane are typically stored in multiple 30,000 gallon steel tanks located above ground and, when necessary, supported by concrete piers. In a few cases, storage of liquefied propane or butane has been accomplished in mined caverns within impervious rock strata deep under the surface of the ground.
It is therefore a purpose of the present invention to provide a unique storage system for energy producing fluids, such as, liquefied and compressed gasses.
It is a further purpose of the present invention to utilize an inactive or abandoned railroad, highway or aqueduct tunnel for the storage of large volumes of (a) compressed air, or (b) gaseous fuel in the form of compressed or liquefied natural gas, or (c) liquefied propane or butane.
It is another purpose of the present invention to provide energy producing gases during peak energy demand periods as a source of energy.
It is still another purpose of the present invention to introduce energy producing fluids into storage during off-peak periods.
It is yet another purpose of the present invention to store energy producing gases in compressed or liquid state during off-peak periods with the ability to discharge such gases at high rates during peak periods of demand.
It is still yet another purpose of the present invention to store large volumes of liquefied propane or butane with the ability to discharge such liquefied gases at rates as may be required from time to time.
It is still another purpose of the present invention to perform all of the above referenced energy storage activities and energy deliveries in an environmentally benign method.
The invention in one aspect comprises a structure for storing energy producing fluids, comprising a substantially horizontal opening through the surface of the earth having an opening at each end with at least one storage vessel mounted therein for the storage of an energy producing fluid.
The invention in another aspect comprises a fluid storage facility, comprising: (a) a substantially horizontal tunnel providing ground level access at each end and originally constructed through the surface of the earth for another purpose; and (b) rehabilitating said tunnel to act as a shell for containing the fluid for a storage facility.
The invention in yet another aspect comprises a fluid storage facility, comprising, a substantially horizontal tunnel providing ground level access at each end and originally constructed through the surface of the earth for another purpose, wherein the interior surface of said tunnel is rehabilitated to permit the containment of a fluid storage facility.
The invention in still yet another aspect comprises a fluid storage facility, comprising, a substantially horizontal tunnel providing ground level access at each end and originally constructed through the surface of the earth for another purpose.
The above and other beneficial purposes, advantages and aspects of the present invention are most effectively attained as described in the specifications and in conjunction with the claims.